Movable body apparatus, exposure apparatus, exposure method, and device manufacturing method

ABSTRACT

A fine movement stage is driven by a controller, based on positional information of the fine movement stage in a measurement direction measured by a measurement system and correction information of a measurement error caused by a tilt of the fine movement stage included in the positional information. Accordingly, driving the fine movement stage with high precision becomes possible, which is not affected by a measurement error included in the positional information in a measurement direction of the measurement system that occurs due to a tilt of the fine movement stage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims the benefit of ProvisionalApplication No. 61/179,856 filed May 20, 2009, the disclosure of whichis hereby incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to movable body apparatus, exposureapparatus, exposure methods, and device manufacturing methods, and moreparticularly, to a movable body apparatus including a movable body whichis movable along a two-dimensional plane, an exposure apparatus equippedwith the movable body apparatus, an exposure method in which an energybeam is irradiated on an object on the movable body to form apredetermined pattern, and a device manufacturing method which uses theexposure apparatus or the exposure method.

2. Description of the Background Art

Conventionally, in a lithography process for manufacturing electrondevices (microdevices) such as semiconductor devices (such as integratedcircuits) and liquid crystal display devices, exposure apparatuses suchas a projection exposure apparatus by a step-and-repeat method (aso-called stepper) and a projection exposure apparatus by astep-and-scan method (a so-called scanning stepper (which is also calleda scanner) are mainly used.

In these types of exposure apparatuses, the position of a wafer stagewhich moves two-dimensionally, holding a sensitive object (hereinaftergenerally referred to as a wafer) such as a wafer or a glass plate onwhich a pattern is formed, was measured by a laser interferometer ingeneral. However, requirements for a wafer stage position controlperformance with higher precision are increasing due to finer patternsthat accompany higher integration of semiconductor devices recently, andas a consequence, short-term variation of measurement values due totemperature fluctuation and/or the influence of temperature gradient ofthe atmosphere on the beam path of the laser interferometer can nolonger be ignored.

To improve such an inconvenience, various inventions related to anexposure apparatus that has employed an encoder having a measurementresolution at the same level or better than a laser interferometer asthe position measuring device of the wafer stage have been proposed(refer to, for example, U.S. Patent Application Publication No.2008/0088843). However, in the liquid immersion exposure apparatusdisclosed in U.S. Patent Application Publication No. 2008/0088843 andthe like, there still were points that should have been improved, suchas a threat of the wafer stage (a grating installed on the wafer stageupper surface) being deformed when influenced by heat of vaporizationand the like when the liquid evaporates.

To improve such an inconvenience, for example, in U.S. PatentApplication Publication No. 2008/0094594, as a fifth embodiment, anexposure apparatus is disclosed which is equipped with an encoder systemthat has a grating arranged on the upper surface of a wafer stageconfigured by a light transmitting member and measures the displacementof the wafer stage related to the periodic direction of the grating bymaking a measurement beam from an encoder main body placed below thewafer stage enter the wafer stage and be irradiated on the grating, andby receiving a diffraction light which occurs in the grating. In thisapparatus, because the grating is covered with a cover glass, thegrating is immune to the heat of vaporization, which makes it possibleto measure the position of the wafer stage with high precision.

However, it was difficult to employ the placement of the encoder mainbody related to the fifth embodiment of Patent Application PublicationNo 2008/0094594 in the case of measuring positional information of afine movement stage in a so-called coarse/fine movement structure, whichincludes a coarse movement stage that moves on a surface plate and afine movement stage that holds a wafer and moves on the coarse movementstage. This was because the coarse movement stage placed above thesurface plate interferes with the measurement beam from the encodermain, body which is irradiated on the fine movement stage placed furtherabove.

Further, while it is desirable to measure positional information of thewafer stage within the two-dimensional plane the same as the exposurepoint on the wafer surface when exposure to the wafer on the wafer stageis performed, in the case when the wafer stage is inclined with respectto the two-dimensional plane, measurement errors which are caused by aheight difference of a wafer surface and a placement surface of thegrating would be included, for example, in measurement values of anencoder which measures the position of the wafer stage from below.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provideda movable body apparatus, comprising: a movable body which is movablesubstantially along a predetermined plane holding an object, and has agrating placed on a plane on a rear surface side of the objectsubstantially parallel with the predetermined plane; a measurementsystem which irradiates a measurement light of a predeterminedwavelength toward the grating from outside on an opposite side of amounting surface of the object, receives diffraction light from thegrating originating from the measurement light, and measures positionalinformation of the movable body in a measurement direction within thepredetermined plane; and a drive system which drives the movable body,based on positional information in the measurement direction of themovable body and correction information of a measurement error caused bya tilt of the movable body included in the positional information.

According to the apparatus, the movable body is driven by the drivesystem; based on the positional information in the measurement directionof the movable body measured by the measurement system and thecorrection information of the measurement error caused by a tilt of themovable body included in the positional information. Accordingly,driving the movable body with high precision becomes possible, which isnot affected by a measurement error included in the positionalinformation in a measurement direction of the measurement system thatoccurs due to a tilt of the movable body.

According to a second aspect of the present invention, there is providedan exposure apparatus that forms a pattern on an object by anirradiation of an energy beam, the apparatus comprising: a patterningdevice that irradiates the energy beam on the object; and the movablebody apparatus of the present invention in which the object on which anenergy beam is irradiated is held by the movable body.

According to the exposure apparatus, because the movable body holdingthe object on which the energy beam is irradiated is driven with highprecision by the movable body apparatus of the present invention, byirradiating the energy beam on the object from the patterning device,exposure with high precision of the object, or more specifically,forming a pattern with high precision becomes possible.

According to a third aspect of the present invention, there is provideda device manufacturing method, including exposing a substrate using theexposure apparatus of the present invention; and developing thesubstrate which has been exposed.

According to a fourth aspect of the present invention, there is providedan exposure method in which an energy beam is irradiated on an object toform a predetermined pattern on the object, the method comprising:measuring positional information of a movable body in a measurementdirection within a predetermined plane by moving the movable body thatholds the object, and also has a grating placed along a surfacesubstantially parallel to a predetermined plane on a rear surface sideof the object, along the predetermined plane, irradiating a measurementlight of the predetermined wavelength toward the grating from outsidethe movable body on an opposite side of a mounting surface of theobject, and receiving a diffraction light from the grating originatingfrom the measurement light; and driving the movable body, based onpositional information in the measurement direction of the movable bodyand correction information of a measurement error caused by a tilt ofthe movable body included in the positional information.

According to the method, the movable body is driven, based on thepositional information in the measurement direction of the movable bodywhich is measured and the correction information of the measurementerror occurring due to a tilt of the movable body included in thepositional information. Accordingly, driving the movable body with highprecision becomes possible, which is not affected by a measurement errorincluded in the positional information in a measurement direction of themeasurement system that occurs due to a tilt of the movable body.

According to a fifth aspect of the present invention, there is provideda device manufacturing method, including exposing a substrate using theexposure method of the present invention; and developing the substratewhich has been exposed.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings;

FIG. 1 is a view that schematically shows a configuration of an exposureapparatus of an embodiment;

FIG. 2A shows a side view of a stage unit which the exposure apparatusin FIG. 1 is equipped with when viewed from a −Y direction, and FIG. 2Bis the stage device shown in a planar view;

FIG. 3 is a block diagram showing a configuration of a control system ofthe exposure apparatus in FIG. 1;

FIG. 4 is a planar view showing a placement of a magnet unit and a coilunit that structure a fine movement stage drive system;

FIG. 5A is a view used to explain an operation when a fine movementstage is rotated around the Z-axis with respect to a coarse movementstage, FIG. 5B is a view used to explain an operation when a finemovement stage is rotated around the Y-axis with respect to a coarsemovement stage, and FIG. 5C is a view used to explain an operation whena fine movement stage is rotated around the X-axis with respect to acoarse movement stage;

FIG. 6 is a view used to explain an operation when a center section ofthe fine movement stage is deflected in the +Z direction;

FIG. 7A is a view showing a rough configuration of an X head 77 x, andFIG. 7B is a view used to explain a placement of each of the X head 77x, Y heads 77 ya and 77 yb inside the measurement arm;

FIG. 8A shows a perspective view of a tip of a measurement arm, and FIG.8B is a planar view when viewed from the +Z direction of an uppersurface of the tip of the measurement arm;

FIG. 9 is a graph showing a measurement error of an encoder with respectto a Z position of the fine movement stage in pitching amount θx;

FIG. 10A is a view used to explain a drive method of a wafer at the timeof scanning exposure, and FIG. 10B is a view used to explain a drivingmethod of a wafer at the time of stepping; and

FIG. 11 is a view showing a placement of the grating related to amodified example.

DESCRIPTION OF THE EMBODIMENTS

An embodiment of the present invention will be described below, withreference to FIGS. 1 to 10B.

FIG. 1 shows a schematic configuration of an exposure apparatus 100 inthe embodiment. Exposure apparatus 100 is a projection exposureapparatus by the step-and-scan method, or a so-called scanner. As itwill be described later, a projection optical system PL is arranged inthe embodiment, and in the description below, a direction parallel to anoptical axis AX of projection optical system PL will be described as theZ-axis direction, a direction within a plane orthogonal to the Z-axisdirection in which a reticle and a wafer are relatively scanned will bedescribed as the Y-axis direction, a direction orthogonal to the Z-axisdirection and the Y-axis direction will be described as the X-axisdirection, and rotational (inclination) directions around the X-axis,the Y-axis, and the Z-axis will be described as θ x, θ y, and θ zdirections, respectively.

Exposure apparatus 100 is equipped with an illumination system 10, areticle stage RST, a projection unit PU, a local liquid immersion device8, a stage device 50 which has a fine movement stage WFS (also referredto as a table), and a control system of these sections and the like. InFIG. 1, a wafer W is mounted on fine movement stage WFS.

Illumination system 10 includes a light source, an illuminanceuniformity optical system, which includes an optical integrator and thelike, and an illumination optical system that has a reticle blind andthe like (none of which are shown), as is disclosed in, for example,U.S. Patent Application Publication No. 2003/0025890 and the like.Illumination system 10 illuminates a slit-shaped illumination area IARwhich is set on a reticle R with a reticle blind (also referred to as amasking system) by an illumination light (exposure light) IL with asubstantially uniform illuminance. Here, as an example, ArF excimerlaser light (with a wavelength of 193 nm) is used as illumination lightIL.

On reticle stage RST, reticle R on which a circuit pattern or the likeis formed on its pattern surface (the lower surface in FIG. 1) is fixed,for example, by vacuum chucking. Reticle stage RST is finely drivablewithin an XY plane, for example, by a reticle stage drive section 11(not shown in FIG. 1, refer to FIG. 3) that includes a linear motor orthe like, and reticle stage RST is also drivable in a scanning direction(in this case, the Y-axis direction, which is the lateral direction ofthe page surface in FIG. 1) at a predetermined scanning speed.

The positional information (including rotation information in the θ zdirection) of reticle stage RST in the XY plane is constantly detected,for example, at a resolution of around 0.25 nm by a reticle laserinterferometer (hereinafter referred to as a “reticle interferometer”)13, via a movable mirror 15 (the mirrors actually arranged are a Ymovable mirror (or a retro reflector) that has a reflection surfacewhich is orthogonal to the Y-axis direction and an X movable mirror thathas a reflection surface orthogonal to the X-axis direction) fixed onreticle stage RST. The measurement values of reticle interferometer 13are sent to a main controller 20 (not shown in FIG. 1, refer to FIG. 3).Incidentally, positional information of reticle stage RST can bemeasured by an encoder system as is disclosed in, for example, U.S.Patent Application Publication 2007/0288121 and the like.

Projection unit PU is placed below reticle stage RST (on the −Z side) inFIG. 1. Projection unit PU is supported via a flange portion provided inthe outer periphery of the projection unit, by a main frame (also calleda metrology frame) BD supported horizontally by a support member (notshown). Projection unit PU includes a barrel 40, and projection opticalsystem PL consisting of a plurality of optical elements held by barrel40. As projection optical system PL, for example, a both-sidetelecentric dioptric system that has a predetermined projectionmagnification (such as one-quarter, one-fifth, or one-eighth times) isused. Therefore, when illumination system 10 illuminates illuminationarea IAR on reticle R with illumination area IL, by illumination lightIL which has passed through reticle R placed so that its pattern surfacesubstantially coincides with a first surface (object surface) ofprojection optical system PL, a reduced image of the circuit pattern ofreticle R within illumination area IAR via projection optical system PL(projection unit PU) is formed on a wafer W whose surface is coated witha resist (a sensitive agent) and is placed on a second surface (imageplane surface) side of projection optical system PL, on an area(hereinafter also referred to as an exposure area) IA conjugate withillumination area IAR. And by reticle stage RST and fine movement stageWFS being synchronously driven, reticle R is relatively moved in thescanning direction (the Y-axis direction) with respect to illuminationarea IAR (illumination light IL) while wafer W is relatively moved inthe scanning direction (the Y-axis direction) with respect to exposurearea IA (illumination light IL), thus scanning exposure of a shot area(divided area) on wafer W is performed, and the pattern of reticle R istransferred onto the shot area. That is, in the embodiment, the patternof reticle R is generated on wafer W according to illumination system 10and projection optical system PL, and then by the exposure of thesensitive layer (resist layer) on wafer W with illumination light IL,the pattern is formed on wafer W. Now, projection unit PU is held by amain frame BD, and in the embodiment, main frame BD is supported almosthorizontally by a plurality of (e.g., three or four) support memberswhich are each placed on an installation surface (floor surface) via avibration isolation mechanism. Incidentally, the vibration isolationmechanism can be placed between each of the support members and mainframe BD. Further, as is disclosed in, for example, PCT InternationalPublication 2006/038952, projection unit PU can be supported bysuspension with respect to a main frame member or to a reticle base (notshown), placed above projection unit PU.

Local liquid immersion device 8 includes a liquid supply device 5, aliquid recovery device 6 (both of which are not shown in FIG. 1, referto FIG. 3), a nozzle unit 32 and the like. As shown in FIG. 1, nozzleunit 32 is supported in a suspended state by a main frame BD supportingprojection unit PU and the like via a support member (not shown) so thatthe periphery of the lower end portion of barrel 40 that holds anoptical element closest to the image plane side (the wafer W side)constituting projection optical system PL, in this case, a lens(hereinafter also referred to as a “tip lens”) 191, is enclosed. In theembodiment, main controller 20 controls liquid supply device 5 (refer toFIG. 3) and supplies a liquid Lq (refer to FIG. 1) between tip lens 191and water W via nozzle unit 32, as well as control liquid recoverydevice 6 (refer to FIG. 3), and recovers liquid Lq from between tip lens191 and wafer W via nozzle unit 32. During the operations, maincontroller 20 controls liquid supply device 5 and liquid recovery device6 so that the quantity of liquid supplied constantly equals the quantityof liquid which has been recovered. Accordingly, a constant quantity ofliquid Lq (refer to FIG. 1) is held constantly replaced in the spacebetween tip lens 191 and wafer W. In the embodiment, as liquid Lq above,pure water that transmits the ArF excimer laser beam (light with awavelength of 193 nm) is to be used.

As shown in FIG. 1, stage device 50 is equipped with a base board 12which is almost horizontally supported by a vibration isolationmechanism (omitted in drawings) on the floor surface, a wafer stage WSTwhich moves on base board 12 holding wafer W, a wafer stage drive system53 (refer to FIG. 3), various measurement systems (16, 70 (refer to FIG.3) and the like) and the like.

Base board 12 is made of a member having a tabular form whose degree offlatness of the upper surface is extremely high, and serves as a guidesurface when wafer stage WST moves.

As shown in FIGS. 1, 2A and the like, wafer stage WST has a wafer coarsemovement stage (hereinafter, shortly referred to as a coarse movementstage) WCS, which is supported by levitation above base board 12 by aplurality of non-contact bearings (e.g., air bearings (omitted indrawings)) provided on its bottom surface and is driven in an XYtwo-dimensional direction by a coarse movement stage drive system 51(refer to FIG. 3) which configures a part of wafer stage drive system53, and a wafer fine movement stage (hereinafter, shortly referred to asa fine movement stage) WFS, which is supported in a non-contact mannerby coarse movement stage WCS and is relatively movable with respect tocoarse movement stage WCS. Fine movement stage WFS is driven by a finemovement stage drive system 52 (refer to FIG. 3), which configures apart of wafer stage drive system 53, with respect to coarse movementstage WCS in the X-axis direction, the Y-axis direction, the Z-axisdirection, the θx direction, the θy direction, and the θz direction(hereinafter expressed as directions of six degrees of freedom, ordirections of six degrees of freedom (X, Y, Z, θx, θy, θz)). In theembodiment, wafer stage drive system 53 is configured, including coarsemovement stage drive system 51 and fine movement stage drive system 52.

Positional information (also including rotation information in the θzdirection) in the XY plane of wafer stage WST (coarse movement stageWCS) is measured by a wafer stage position measurement system 16.Further, positional information of fine movement stage WFS in directionsof six degrees of freedom (X, Y, Z, θx, θy, θz) is measured by a finemovement stage position measurement system 70 (refer to FIG. 3).Measurement results (measurement information) of wafer stage positionmeasurement system 16 and fine movement stage position Measurementsystem 70 are supplied to main controller 20 (refer to FIG. 3) forposition control of coarse movement stage WCS and fine movement stageWFS.

Configuration and the like of each part configuring stage device 50including the various measurements system described above will beexplained in detail, later on.

In exposure apparatus 100, a wafer alignment system ALG (not shown inFIG. 1, refer to FIG. 3) is placed at a position a predetermineddistance away on the +Y side from the center of projection unit PU. Asalignment system ALG, for example, an FIA (Field Image Alignment) systemby an image processing method is used. Wafer alignment system ALG isused by main controller 20 on wafer alignment (e.g., Enhanced GlobalAlignment (EGA)) when detecting a second fiducial mark that will bedescribed later formed on a measurement plate on fine movement stageWFS, or when detecting an alignment mark on wafer W. Imaging signals ofwafer alignment system ALG is supplied to main controller 20 via asignal processing system (not shown). Main controller 20 computes X, Ycoordinates of an object mark in a coordinate system at the time ofalignment, based on detection results (imaging results) of alignmentsystem ALG and positional information of fine movement stage WFS (waferW) at the time of detection.

Besides this, in exposure apparatus 100 of the embodiment, a multiplepoint focal point position detection system (hereinafter shortlyreferred to as a multipoint AF system) AF (not shown in FIG. 1, refer toFIG. 3) having a similar configuration as the one disclosed in, forexample, U.S. Pat. No. 5,448,332 and the like, is arranged in thevicinity of projection unit PU. Detection signals of multipoint AFsystem AF are supplied to main controller 20 (refer to FIG. 3) via an AFsignal processing system (not shown) Main controller 20 detectspositional information (surface position information) of the wafer Wsurface in the Z-axis direction at a plurality of detection points ofthe multipoint AF system AF based on detection Signals of multipoint AFsystem AF, and performs a so-called focus leveling control of wafer Wduring the scanning exposure based on the detection results.Incidentally, positional information (unevenness information) of thewafer W surface can be acquired in advance at the time of waferalignment (EGA) by arranging the multipoint AF system in the vicinity ofwafer alignment system ALG, and the so-called focus leveling control ofwafer W can be performed at the time of exposure by using the surfaceposition information and measurement values of a laser interferometersystem 75 (refer to FIG. 3) configuring a part of fine movement stageposition measurement system 70 which will be described later on.Incidentally, measurement values of an encoder system 73 which will bedescribed later configuring fine movement stage position measurementsystem 70 can also be used, rather than laser interferometer system 75in focus leveling control.

Further, above reticle stage RST, as is disclosed in detail in, forexample, U.S. Pat. No. 5,646,413 and the like, a pair of reticlealignment systems RA₁, and RA₂ (reticle alignment system RA₂ is hiddenbehind reticle alignment system RA₁, in the depth of the page surface inFIG. 1.) of an image processing method that uses a light (in theembodiment, illumination light IL) of the exposure wavelength as anillumination light for alignment is placed. Detection signals of reticlealignment detection systems RA₁ and RA₂ are supplied to main controller20 (refer to FIG. 3) via a signal processing system (not shown).Incidentally, reticle alignment systems RA₁ and RA₂ do not have to beprovided. In this case, it is desirable for fine movement stage WFS tohave a detection system in which a light transmitting section(light-receiving section) is installed so as to detect a projectionimage of the reticle alignment mark, as disclosed in, for example, U.S.Patent Application Publication No. 2002/0041377 and the like.

FIG. 3 shows the main configuration of the control system of exposureapparatus 100. The control system is mainly configured of maincontroller 20. Main controller 20 includes a workstation (or amicrocomputer) and the like, and has overall control over each part ofexposure apparatus 100, such as local liquid immersion device 8, coarsemovement stage drive system 51, and fine movement stage drive system 52previously described.

Now, a configuration and the like of stage device 50 will be describedin detail. As shown in FIGS. 2A and 2B, coarse movement stage WCS isequipped with a rectangular plate shaped coarse movement slider section91 whose longitudinal direction is in the X-axis direction in a planarview (when viewing from the +Z direction), a rectangular plate shapedpair of side wall sections 92 a and 92 b which are each fixed on theupper surface of coarse movement slider section 91 on one end and theother end in the longitudinal direction in a state parallel to the YZsurface, with the Y-axis direction serving as the longitudinaldirection, and a pair of stator sections 93 a and 93 b that are eachfixed on the upper surface of side wall sections 92 a and 92 b. As awhole, coarse movement stage WCS has a box like shape having a lowheight whose upper surface in a center in the X-axis direction andsurfaces on both sides in the Y-axis direction are open. Morespecifically, in coarse movement stage WCS, a space is formed insidepenetrating in the Y-axis direction.

on the bottom surface of coarse movement stage WCS the bottom surface ofcoarse movement slider section 91), a magnet unit is fixed consisting ofa plurality of permanent magnets placed in the shape of a matrix, asshown in FIG. 2A. In correspondence with the magnet unit, inside base12, a coil unit is housed, including a plurality of coils 14 placed inthe shape of a matrix with the XY two-dimensional direction serving as arow direction and a column direction, as shown in FIG. 1. The magnetunit configures a coarse movement stage drive system 51 consisting of aplanar motor employing a Lorentz electromagnetic drive method as isdisclosed in, for example, U.S. Pat. No. 5,196,745, along with the coilunit of base board 12. The magnitude and direction of current suppliedto each of the coils 14 configuring the coil unit are controlled by maincontroller 20 (refer to FIG. 3). Coarse movement stage WCS is supportedby levitation on base board 12, via a clearance of around several μm, bythe air bearings previously described fixed in the periphery of thebottom surface of coarse movement slider section 91 in which the magnetunit described above was provided, and is driven in the X-axisdirection, the Y-axis direction, and the θz direction, by coarsemovement stage drive system 51. Incidentally, as coarse movement stagedrive system 51, the drive method is not limited to the planar motorusing the Lorentz electromagnetic force drive method, and for example, aplanar motor by a variable reluctance drive system can also be used.Incidentally, the electromagnetic force in the electromagnetic forcedrive method is not limited to the'Lorentz force. Besides this, coarsemovement stage drive system 51 can be configured by a planar motor of amagnetic levitation type. In this case, the air bearings will not haveto be arranged on the bottom surface of coarse movement slider section91.

As shown in FIGS. 2A and 2B, the pair of stator sections 93 a and 93 bis each made of a member with a tabular outer shape, and in the inside,coil units CUa and CUb are housed to drive fine movement stage WFS. Themagnitude and direction of current supplied to each of the coilsconfiguring coil units CUa and Cub are controlled by main controller 20(refer to FIG. 3). The configuration of coil units CUa and CUb will bedescribed further, later in the description.

As shown in FIGS. 2A and 2B, the pair of stator sections 93 a and 93 beach have a rectangle tabular shape whose longitudinal direction is inthe y-axis direction. Stator section 93 a has an end on the +X sidefixed to the upper surface of side wall section 92 a, and stator section93 b has an end on the −X side fixed to the upper surface of side wallsection 92 b.

As shown in FIGS. 2A and 2B, fine movement stage WFS is equipped with amain body section 81 consisting of an octagonal plate shape member whoselongitudinal direction is in the X-axis direction in a planar view, anda pair of mover sections 82 a and 82 b that are each fixed to one endand the other end of main body section 81 in the longitudinal direction.

Main body section 81 is formed of a transparent material through whichlight can pass, so that a measurement beam (a laser beam) of an encodersystem which will be described later can proceed inside the main bodysection. Further, main body section 81 is formed solid (does not haveany space inside) in order to reduce the influence of air fluctuation tothe laser beam inside the main body section. Incidentally, it ispreferable for the transparent material to have a low thermal expansion,and as an example in the embodiment, synthetic quarts (glass) is used.Incidentally, main body section 81 can be structured all by thetransparent material or only the section which the measurement beam ofthe encoder system passes through can be structured by the transparentmaterial, and only the section which this measurement beam passesthrough can be formed solid.

In the center of the upper surface of main body section 81 (to be moreprecise, a cover glass which will be described later) of fine movementstage WFS, a wafer holder (not shown) is arranged which holds wafer W byvacuum suction or the like. In the embodiment, for example, a waferholder of a so-called pin chuck method on which a plurality of supportsections (pin members) supporting wafer W are formed within a loopshaped projecting section (rim section) is used, and grating RG to bedescribed later is provided on the other surface (rear surface) of thewafer holder whose one surface (surface) is a wafer mounting surface.Incidentally, the wafer holder can be formed integrally with finemovement stage WFS, or can be fixed to main body section 81, forexample, via an electrostatic chuck mechanism, a clamping mechanism, orby adhesion and the like.

Furthermore, on the upper surface of main body section 81 on the outerside of the wafer holder (mounting area of wafer W), as shown in FIGS.2A and 2B, a plate (a liquid repellent plate) 83 is attached that has acircular opening one size larger than wafer W (the wafer holder) formedin the center, and also has an octagonal outer shape (contour)corresponding to main body section 81. A liquid repellent treatmentagainst liquid Lq is applied to the surface of plate 83 (a liquidrepellent surface is formed). Plate 83 is fixed to the upper surface ofmain body section 81, so that its entire surface (or a part of itssurface) becomes substantially flush with the surface of wafer W.Further, in plate 83, a circular opening is formed at one end as shownin FIG. 2B, and inside this opening, a measurement plate 86 is embeddedin a state where its surface is substantially flush with the surface ofplate 83, or more specifically, the surface of wafer W. On the surfaceof measurement plate 86, at least the pair of first fiducial markspreviously described, and a second fiducial mark detected by waferalignment system ALG are formed (both the first and second fiducialmarks are omitted in the drawing). Incidentally, instead of attachingplate 83 to main body section 81, for example, the wafer holder can beformed integrally with fine movement stage WFS, and a liquid repellenttreatment can be applied to the upper surface of fine movement stage WFSin a periphery area (an area the same as plate 83 (can include thesurface of measurement plate 86) surrounding the wafer holder.

As shown in FIG. 2A, on the upper surface of main body section 81, atwo-dimensional grating (hereinafter merely referred to as a grating) RGis placed horizontally (parallel to the wafer N surface). Grating RG isfixed (or formed) on the upper surface of main body section 81consisting of a transparent material. Grating RG includes a reflectiondiffraction grating (X diffraction grating) whose periodic direction isin the X-axis direction and a reflection diffraction grating (Ydiffraction grating) whose periodic direction is in the Y-axisdirection. In the embodiment, the area (hereinafter, forming area) onmain body section 81 where the two-dimensional grating is fixed orformed, as an example, is in a circular shape which is one size largerthan wafer W.

Grating RG is covered and protected with a protective member, such as,for example, a cover glass 84. In the embodiment, on the upper surfaceof cover glass 84, the electrostatic chuck mechanism previouslydescribed to hold the wafer holder by suction is provided. Incidentally,in the embodiment, while cover glass 84 is provided so as to coveralmost the entire surface of the upper surface of main body section 81,cover glass 84 can be arranged so as to cover only a part of the uppersurface of main body section 81 which includes grating RG. Further,while the protective member (cover glass 84) can be formed of the samematerial as main body section 81, besides this, the protective membercan be formed of, for example, metal or ceramics. Further, although aplate shaped protective member is desirable because a sufficientthickness is required to protect grating RG, a thin film protectivemember can also be used depending on the material.

Incidentally, of the forming area of grating RG, on a surface of coverglass 84 corresponding to an area where the forming area spreads to theperiphery of the wafer holder, it is desirable, for example, to providea reflection member (e.g., a thin film and the like) which covers theforming area, so that the measurement beam of the encoder systemirradiated on grating RG does not pass through cover glass 84, or morespecifically, so that the intensity of the measurement beam does notchange greatly in the inside and the outside of the area on the rearsurface of the wafer holder.

As it can also be seen from FIG. 2A, main body section 81 consists of anoverall octagonal plate shape member that has an extending section whichextends outside on one end and the other end in the longitudinaldirection, and on its bottom surface, a recessed section is formed atthe section facing grating RG. Main body section 81 is formed so thatthe center area where grating RG is arranged is formed in a plate shapewhose thickness is substantially uniform.

On the upper surface of each of the extending sections on the +X sideand the −X side of main body section 81, spacers 85 a and 85 b having aprojecting shape when sectioned are provided, with each of theprojecting sections 89 a and 89 b extending outward in the Y-axisdirection.

As shown in FIGS. 2A and 2E, mover section 82 a includes two plate-likemembers 82 a ₁ and 82 a ₂ having a rectangular shape in a planar viewwhose size (length) in the Y-axis direction and size (width) in theX-axis direction are both shorter than stator section 93 a (around halfthe size). Plate-like members 82 a ₁ and 82 a ₂ are both fixed parallelto the XY plane, in a state set apart only by a predetermined distancein the Z-axis direction (vertically), via projecting section 89 a ofspacer 85 a previously described, with respect to the end on the +X sideof main body section 81. In this case, the −X side end of plate-likemember 82 a ₂ is clamped by spacer 85 a and the extending section on the+X side of main body section 81. Between the two plate-like members 82 a_(a) and 82 a ₂, an end on the −X side of stator section 93 a isinserted in a non-contact manner. Inside plate-like members 82 a ₁ and82 a ₂, magnet units MUa₁ and MUa₂ which will be described later arehoused.

Mover section 82 b includes two plate-like members 82 b ₁ and 82 b ₂maintained at a predetermined distance in the Z-axis direction(vertically), and is configured in a similar manner with mover section82 a, although being symmetrical. Between the two plate-like members 82b ₁, and 82 b ₂, an end on the +X side of stator section 93 b isinserted in a non-contact manner. Inside plate-like members 82 b ₁ and82 b ₂, magnet units MUb₁ and MUb₂ are housed, which are configuredsimilar to magnet units MUa₁ and MUa₂.

Now, as is previously described, because the surface on both sides inthe Y-axis direction of coarse movement stage WCS is open, whenattaching fine movement stage WFS to coarse movement stage WCS, theposition of fine movement stage WFS in the Z-axis direction should bepositioned so that stator section 93 a, 93 b are located betweenplate-like members 82 a ₁ and 82 a ₂, and 82 b ₁ and 82 b ₂,respectively, and then fine movement stage WFS can be moved (slid) inthe Y-axis direction after this positioning.

Fine movement stage drive system 52 includes the pair of magnet unitsMUa₁ and MUa₂ that mover section 82 a previously described has, coilunit CUa that stator section 93 a has, the pair of magnet units MUb₁ andMUb₂ that mover section 82 b has, and coil unit CUb that stator section93 b has.

This will be explained further in detail. As it can be seen from FIG. 4,inside stator section 93 a at the end on the −X side, two lines of coilrows are placed a predetermined distance apart in the X-axis direction,which are a plurality of (in this case, twelve) YZ coils (hereinafterappropriately referred to as “coils”) 55 and 57 that have a rectangularshape in a planar view and are placed equally apart in the Y-axisdirection. YZ coil 55 has an upper part winding and a lower part windingin a rectangular shape in a planar view that are disposed such that theyoverlap in the vertical direction (the Z-axis direction). Further,between the two lines of coil rows described above inside stator section93 a, an X coil (hereinafter shortly referred to as a “coil” asappropriate) 56 is placed, which is narrow and has a rectangular shapein a planar view and whose longitudinal direction is in the Y-axisdirection. In this case, the two lines of coil rows and X coil 56 areplaced equally spaced in the X-axis direction. Coil unit CUa isconfigured including the two lines of coil rows and X coil 56.

Incidentally, in the description below, while one of the stator sections93 a and mover sections 82 a, which have coil unit Cue and magnet unitsMUa₁ and MUa₂, respectively, will be described using FIG. 4, the other(the −X side) stator section 93 b and mover section 82 b will bestructured similar to these sections and will function in a similarmanner. Accordingly, coil unit CUb, and magnet units MUb₁ and MUb₂ arestructured similar to coil unit CUa, and magnet units MUa₁ and MUa₂.

Inside plate-like member 82 a ₁ on the +Z side configuring a part ofmovable section 82 a, as it can be seen when referring to FIG. 4, twolines of magnet rows are placed a predetermined distance apart in theX-axis direction, which are a plurality of (in this case, ten) permanentmagnets 65 a and 67 a that have a rectangular shape in a planar view andwhose longitudinal direction is in the X-axis direction. The two linesof magnet rows are placed facing coils 55 and 57, respectively. Further,between the two lines of magnet rows described above inside plate-likemember 82 a ₁, a pair (two) of permanent magnets 66 a ₁ and 66 a ₂ whoselongitudinal direction is in the Y-axis direction is placed set apart inthe X axis direction, facing coil 56.

The plurality of permanent magnets 65 a is placed in an arrangementwhere the magnets have a polarity which is alternately a reversepolarity to each other. The magnet row consisting of the plurality ofpermanent magnets 67 a is structured similar to the magnet rowconsisting of the plurality of permanent magnets 65 a. Further,permanent magnets 66 a ₁ and 66 a ₂ are placed so that the polarity toeach other is a reverse polarity. Magnet unit MUa₁ is configured by theplurality of permanent magnets 65 a and 67 a, and 66 a ₁ and 66 a ₂.

Also inside plate-like member 82 a ₂ on the −Z side, permanent magnetsare placed in a similar arrangement as in the inside of plate-likemember 82 a ₁ described above, and magnet unit MUa₂ is configured bythese permanent magnets.

Now, as for the plurality of permanent magnets 65 a placed adjacently inthe Y-axis direction, positional relation (each distance) in the Y-axisdirection between the plurality of permanent magnets 65 and theplurality of YZ coils 55 is set so that when two adjacent permanentmagnets (referred to as a first and second permanent magnet for the sakeof convenience) 65 a each face the winding section of YZ coil (referredto as a first YZ coil for the sake of convenience) 55, then a thirdpermanent magnet 65 a adjacent to these permanent magnets does not facethe winding section of a second YZ coil 55 adjacent to the first YZ coil55 described above (so that the permanent magnet faces the hollow centerin the center of the coil, or faces a core to which the coil is wound,such as an iron core) In this case, a fourth permanent magnet 65 a and afifth permanent magnet 65 a 5 which are each adjacent to the thirdpermanent magnet 65 a, face the winding section of a third YZ coil 55,which is adjacent to the second YZ coil 55. The distance in the Y-axisdirection between permanent magnets 67 a, and the two lines of permanentmagnet rows inside plate-like member 82 a ₂ on the −Z side is alsosimilar.

Because a placement of each of the coils and permanent magnets as in thedescription above is employed in the embodiment, main controller 20 candrive fine movement stage WFS in the Y-axis direction by supplying anelectric current alternately to the plurality of YZ coils 55 and 57 thatare arranged in the Y-axis direction. Further, along with this, bysupplying electric current to coils of YZ coils 55 and 57 that are notused to drive fine movement stage WFS in the Y-axis direction, maincontroller 20 can generate a drive force in the Z-axis directionseparately from the drive force in the Y-axis direction and make finemovement stage WFS levitate from coarse movement stage WCs. And, maincontroller 20 drives fine movement stage WFS in the Y-axis directionwhile maintaining the levitated state of fine movement stage WFS withrespect to coarse movement stage WCS, namely a noncontact state, bysequentially switching the coil subject to current supply according tothe position of fine movement stage WFS in the Y-axis direction.Further, main controller 20 can drive fine movement stage WFS in theY-axis direction in a state where fine movement stage WFS is levitatedfrom coarse movement stage WCS, as well as independently drive the finemovement stage in the X-axis direction.

Further, as shown in FIG. 5A, for example, main controller 20 can makefine movement stage WFS rotate around the Z-axis (θz rotation) (refer tothe outlined arrow in FIG. 5A), by applying a drive force (thrust) inthe Y-axis direction having a different magnitude to both Mover section82 a on the +X side and mover section 82 b on the −X side of finemovement stage WFS (refer to the black arrow in FIG. 5A). Incidentally,in contrast with FIG. 5A, by making the drive force applied to moversection 82 a on the +X side larger than the −X side, fine movement stageWFS can be made to rotate counterclockwise with respect to the Z-axis.

Further, as shown in FIG. 5B, main controller 20 can make fine movementstage WFS rotate around the Y-axis (θy drive) (refer to the outlinedarrow in FIG. 5B), by applying a different levitation force (refer tothe black arrows in FIG. 5B) to both mover section 82 a on the +X sideand mover section 82 b on the −X side of fine movement stage WFS.Incidentally, in contrast with FIG. 5B, by making the levitation forceapplied to mover section 82 a larger than the mover section 82 b side,fine movement stage WFS can be made to rotate counterclockwise withrespect to the Y-axis.

Further, as shown in FIG. 5C, for example, main controller 20 can makefine movement stage WFS rotate around the X-axis (ex drive) (refer tothe outlined arrow in FIG. 5C), by applying a different levitation forceto both mover sections 82 a and 82 b of fine movement stage WFS on the +side and the − side in the Y-axis direction (refer to the black arrow inFIG. 5C). Incidentally, in contrast with FIG. 5C, by making thelevitation force applied to mover section 82 a (and 82 b) on the −Y sidesmaller than the levitation force on the +Y side, fine movement stageWFS can be made to rotate counterclockwise with respect to the X-axis.

As it can be seen from the description above, in the embodiment, finemovement stage drive system 52 supports fine movement stage WFS bylevitation in a non-contact state with respect to coarse movement stageWCS, and can also drive fine movement stage WFS in a non-contact mannerin directions of six degrees of freedom (X, Y, Z, θx, θy, θz) withrespect to coarse movement stage WCS.

Further, in the embodiment, by supplying electric current to the twolines of coils 55 and 57 (refer to FIG. 4) placed inside stator section93 a in directions opposite to each other when applying the levitationforce to fine movement stage WFS, for example, main controller 20 canapply a rotational force (refer to the outlined arrow in FIG. 6) aroundthe Y-axis simultaneously with the levitation force (refer to the blackarrow in FIG. 6) with respect to mover section 82 a, as shown in FIG. 6.Similarly, by supplying electric current to the two lines of coils 55and 57 placed inside stator section 93 b in directions opposite to eachother when applying the levitation force to fine movement stage WFS, forexample, main controller 20 can apply a rotational force around theY-axis simultaneously with the levitation force with respect to moversection 82 a.

Further, by applying a rotational force around the Y-axis (a force inthe θy direction) to each of the pair of mover sections 82 a and 82 b indirections opposite to each other, main controller 20 can deflect thecenter in the X-axis direction of fine movement stage WFS in the +Zdirection or the −Z direction (refer to the hatched arrow in FIG. 6).Accordingly, as shown in FIG. 6, by bending the center in the X-axisdirection of fine movement stage WFS in the +Z direction (in a convexshape), the deflection in the middle part of fine movement stage WFS(main body section 81) in the X-axis direction due to the self-weight ofwafer W and main body section 81 can be canceled out, and degree ofparallelization of the wafer W surface with respect to the XY plane(horizontal surface) can be secured. This is particularly effective, inthe case such as when the diameter of wafer W becomes large and finemovement stage WFS also becomes large.

Further, when wafer W is deformed by its own weight and the like, thereis a risk that the surface of wafer W mounted on fine movement stage WFSwill no longer be within the range of the depth of focus of projectionoptical system PL within the irradiation area (exposure area IA) ofillumination light IL. Therefore, similar to the case described abovewhere main controller 20 deflects the center in the X-axis direction offine movement stage WFS to the +Z direction, by applying a rotationalforce around the Y-axis to each of the pair of mover sections 82 a and82 b in directions opposite to each other, wafer W is deformed to besubstantially flat, and the surface of wafer W within exposure area IAcan fall within the range of the depth of focus of projection opticalsystem PL. Incidentally, while FIG. 6 shows an example where finemovement stage WFS is bent in the +Z direction (a convex shape), finemovement stage WFS can also be bent in a direction opposite to this (aconcave shape) by controlling the direction of the electric currentsupplied to the coils.

Incidentally, the method of making fine movement stage WFS (and wafer Wheld by this stage) deform in a concave shape or a convex shape within asurface (XZ plane) perpendicular to the Y-axis can be applied, not onlyin the case of correcting deflection caused by its own weight and/orfocus leveling control, but also in the case of employing asuper-resolution technology which substantially increases the depth offocus by changing the position in the Z-axis direction at apredetermined point within the range of the depth of focus, while thepredetermined point within the shot area of wafer W crosses exposurearea IA, as is disclosed in, for example, U.S. Pat. RE 37391 and thelike.

In exposure apparatus 100 of the embodiment, at the time of exposureoperation by the step-and-scan method to wafer W, positional information(including the positional information in the θz direction) in the XYplane of fine movement stage WFS is measured by main controller 20 usingan encoder system 73 (refer to FIG. 3) of fine movement stage positionmeasurement system 70 which will be described later on. The positionalinformation of fine movement stage WFS is sent to main controller 20,which controls the position of fine movement stage WFS based on thepositional information.

On the other hand, when wafer stage WST (fine movement stage WFS) isoutside the measurement area of fine movement stage position measurementsystem 70, the positional information of wafer stage WST is measured bymain controller 20 using wafer stage position measurement system 16(refer to FIG. 3). As shown in FIG. 1, wafer stage position measurementsystem 16 includes a laser interferometer which irradiates a measurementbeam on a reflection surface formed on the coarse movement stage WCSside surface by mirror polishing and measures positional information ofwafer stage WST in the XY plane. Incidentally, the positionalinformation of wafer stage WST in the XY plane can be measured usingother measurement devices, such as for example, an encoder system,instead of wafer stage position measurement system 16 described above.In this case, for example, a two-dimensional scale can be placed on theupper surface of base board 12, and an encoder head can be attached tothe bottom surface of coarse movement stage WCS.

As shown in FIG. 1, fine movement stage position measurement system 70is equipped with a measurement member (a measurement arm 71) which isinserted in a space inside coarse movement stage WCS in a state wherewafer stage WST is placed below projection optical system PL.Measurement arm 71 is supported cantilevered (supported in the vicinityof one end) by main frame BD via a support section 72. Incidentally, inthe case a configuration is employed where the measurement members donot interfere with the movement of the wafer stage, the configuration isnot limited to the cantilever support, and both ends in the longitudinaldirection can be supported.

Measurement arm 71 is a square column shaped (that is, a rectangularsolid shape) member having a longitudinal rectangular cross sectionwhose longitudinal direction is in the Y-axis direction and size in aheight direction (the Z-axis direction) is larger than the size in awidth direction (the X-axis direction), and is made of a material whichis the same that transmits light, such as, for example, a glass member,which is affixed in plurals. Measurement arm 71 is formed solid, exceptfor the portion where the encoder head (an optical system) which will bedescribed later is housed. In the state where wafer stage WST is placedbelow projection optical system PL as previously described, the tip ofmeasurement arm 71 is inserted into the space of coarse movement stageWCS, and its upper surface faces the lower surface (to be more precise,main body section 81 (not shown in FIG. 1, refer to FIG. 2A and thelike) of fine movement stage WFS as shown in FIG. 1. The upper surfaceof measurement arm 71 is placed almost parallel with the lower surfaceof fine movement stage WFS, in a state where a predetermined clearance,such as, for example, around several mm, is formed with the lowersurface of fine movement stage WFS. Incidentally, the clearance betweenthe upper surface of measurement arm 71 and the lower surface of finemovement stage WFS can be more than or less than several mm.

As shown in FIG. 3, fine movement stage position measurement system 70is equipped with encoder system 73 and laser interferometer system 75.Encoder system 73 includes an X linear encoder 73 x measuring theposition of fine movement stage WFS in the X-axis direction, and a pairof Y linear encoders 73 ya and 73 yb measuring the position of finemovement stage WFS in the Y-axis direction. In encoder system 73, a headof a diffraction interference type is used that has a configurationsimilar to an encoder head (hereinafter shortly referred to as a head)disclosed in, for example, U.S. Pat. No. 7,238,931, U.S. PatentApplication Publication No. 2007/0288121 and the like. However, in theembodiment, a light source and a photodetection system (including aphotodetector) of the head are placed external to measurement arm 71 asin the description later on, and only an optical system is placed insidemeasurement arm 71, or more specifically, facing grating RG.Hereinafter, the optical system placed inside measurement arm 71 will bereferred to as a head, besides the case when specifying is especiallynecessary.

Encoder system 73 measures the position of fine movement stage WFS inthe X-axis direction using one X head 77 x (refer to FIGS. 7A and 7B),and the position in the Y-axis direction using a pair of Y heads 77 yaand 77 yb (refer to FIG. 7B). More specifically, X linear encoder 73 xpreviously described is configured by X head 77 x which measures theposition of fine movement stage WFS in the X-axis direction using an Xdiffraction grating of grating RG, and the pair of Y linear encoders 73ya and 73 yb is configured by the pair of Y heads 77 ya and 77 yb whichmeasures the position of fine movement stage WFS in the Y-axis directionusing a. Y diffraction grating of grating RG.

A configuration of three heads 77 x, 77 ya, and 77 yb which configureencoder system 73 will now be described. FIG. 7A representatively showsa rough configuration of X head 77 x, which represents three heads 77 x,77 ya, and 77 yb. Further, FIG. 7B shows a placement of each of the Xhead 77 x, and Y heads 77 ya and 77 yb within measurement arm 71.

As shown in FIG. 7A, X head 77 x is equipped with a polarization beamsplitter PBS whose separation plane is parallel to the YZ plane, a pairof reflection mirrors R1 a and R1 b, lenses L2 a and L2 b, quarterwavelength plates (hereinafter, described as λ/4 plates) WP1 a and WP1b, reflection mirrors R2 a and R2 b, and reflection mirrors R1 a and R3b and the like, and these optical elements are placed in a predeterminedpositional relation. Y heads 77 ya and 77 yb also have an optical systemwith a similar structure. As shown in FIGS. 7A and 7B, X head 77 x, Yheads 77 ya and 77 yb are each unitized and fixed inside of measurementarm 71A.

As shown in FIG. 7B, in X head 77 x (X encoder 73 x), a laser beam LBx₀is emitted in the −Z direction from a light source LDx provided on theupper surface (or above) at the end on the −Y side of measurement arm71, and its optical path is bent to become parallel with the Y-axisdirection via a reflection surface RP which is provided on a part ofmeasurement arm 71 inclined at an angle of 45 degrees with respect tothe XY plane. This laser beam LBx₀ travels through the solid sectioninside measurement arm 71 in parallel with the longitudinal direction(the Y-axis direction) of measurement arm 71, and reaches reflectionmirror R3 a (refer to FIG. 7A) Then, the optical path of laser beam LBx₀is bent by reflection mirror R3 a and is incident on polarization beamsplitter PBS. Laser beam LBx₀ is split by polarization by polarizationbeam splitter PBS into two measurement beams LBx₁ and LBx₂. Measurementbeam LBx₁ having been transmitted through polarization beam splitter PBSreaches grating RG formed on fine movement stage WFS, via reflectionmirror R1 a, and measurement beam LBx₂ reflected off polarization beamsplitter PBS reaches grating RG via reflection mirror R1 b.Incidentally, “split by polarization” in this case means the splittingof an incident beam into a P-polarization component and anS-polarization component.

Predetermined-order diffraction beams that are generated from grating RGdue to irradiation of measurement beams LBx₁ and LBx₂, such as, forexample, the first-order diffraction beams are severally converted intoa circular polarized light by λ/4 plates WP1 a and WP1 b via lenses L2 aand L2 b, and reflected by reflection mirrors R2 a and R2 b and then thebeams pass through λ/4 plates WP1 a and WP1 b again and reachpolarization beam splitter PBS by tracing the same optical path in thereversed direction.

Each of the polarization directions of the two first-order diffractionbeams that have reached polarization beam splitter PBS is rotated at anangle of 90 degrees with respect to the original direction. Therefore,the first-order diffraction beam of measurement beam LBx₂ having passedthrough polarization beam splitter PBS first, is reflected offpolarization beam splitter PBS. The first-order diffraction beam ofmeasurement beam LBx₂ having been reflected off polarization beamsplitter PBS first, passes through polarization beam splitter PBS. Thiscoaxially synthesizes the first-order diffraction beams of each of themeasurement beams LBx₁ and LBx₂ as a synthetic beam LBx₁₂. Syntheticbeam LBx₁₂ has its optical path bent by reflecting mirror R3 b so itbecomes parallel to the Y-axis, travels inside measurement arm 71parallel to the Y-axis, and then is sent to an X photodetection system74 x provided on the upper surface (or above) at the end on the Y sideof measurement arm 71 shown in FIG. 7B via reflection surface RPpreviously described.

In X photodetection system 74 x, the polarization direction of thefirst-order diffraction beams of beams LBx and LBx₂ synthesized assynthetic beam LBx₁₂ is arranged by a polarizer (analyzer) (not shown)and the beams overlay each other so as to form an interference light,which is detected by the photodetector and is converted into an electricsignal in accordance with the intensity of the interference light. Whenfine movement stage WFS moves in the measurement direction (in thiscase, the X-axis direction) here, a phase difference between the twobeams changes, which changes the intensity of the interference light.This change in the intensity of the interference light is supplied tomain controller 20 (refer to FIG. 3) as positional information relatedto the X-axis direction of fine movement stage WFS.

As shown in FIG. 7B, laser beams LBya₀ and LByb₀, which are emitted fromlight sources LDya and LDyb, respectively, and whose optical paths arebent by an angle of 90 degrees so as to become parallel to the Y-axis byreflection surface RP1 previously described, are incident on Y heads 77ya and 77 yb, and similar to the previous description, from Y heads 77ya and 77 yb, synthetic beams LBya₁₂ and LByb₁₂ of the first-orderdiffraction beams by grating RG (Y diffraction grating) of each of themeasurement beams split by polarization by the polarization beamsplitter are output, respectively, and are returned to Y photodetectionsystem 74 ya, 74 yb. Now, laser beams LBya₀ and LByb₀ emitted from lightsources LDya and LDyb, and synthetic beams LBya₁₂ and LByb₁₂ returningto Y photodetection systems 74 ya and 74 yb, each pass an optical pathwhich are overlaid in a direction perpendicular to the page surface ofFIG. 7B. Further, as described above, in Y heads 77 ya and 77 yb,optical paths are appropriately bent (omitted in drawings) inside sothat laser beams LBya₀ and LByb₀ emitted from the light source andsynthetic beams LBya₁₂ and LByb₁₂ returning to Y photodetection systems74 ya and 74 yb pass optical paths which are parallel and distancedapart in the Z-axis direction.

FIG. 8A shows a tip of measurement arm 71 in a perspective view, andFIG. 8B shows an upper surface of the tip of measurement arm 71 in aplanar view when viewed from the +Z direction. As shown in FIGS. 8A and8B, X head 77 x irradiates measurement beams LBx₁ and LBx₂ (indicated bya solid line in FIG. 8A) from two points (refer to the white circles inFIG. 8B) on a straight line LX parallel to the X-axis that are at anequal distance from a center line CL of measurement arm 71, on the sameirradiation point on grating RG (refer to FIG. 7A). The irradiationpoint of measurement beams LBx₁ and LBx₂, that is a detection point of Xhead 77 x (refer to reference code DP in FIG. 8B) coincides with theexposure position which is the center of irradiation area (exposurearea) IA of illumination light IL irradiated on wafer W (refer to FIG.1). Incidentally, while measurement beams LBx₁ and LBx₂ are actuallyrefracted at a boundary and the like of main body section 81 and anatmospheric layer, it is shown simplified in FIG. 7A and the like.

As shown in FIG. 7B, each of the pair of Y heads 77 ya and 77 yb areplaced on the +X side and the −X side of center line CL. As shown inFIGS. 8A and 8B, Y head 77 ya irradiates measurement beams LBya₁ andLBya₂ that are each shown by a broken line in FIG. 8A on a commonirradiation point on grating RG from two points (refer to the whitecircles in FIG. 8B) which are distanced equally from straight line LX ona straight line LYa which is parallel to the Y-axis. The irradiationpoint of measurement beams LBya₁ and LBya₂, that is, a detection pointof Y head 77 ya is shown by reference code DPya in FIG. 8B.

Y head 77 yb irradiates measurement beams LByb₁ and LByb₂ from twopoints (refer to the white circles in FIG. 8B) which are symmetrical tothe two outgoing points of measurement beams LBya₁, and LBya₂ withrespect to center line CL, on a common irradiation point DPyb on gratingRG. As shown in FIG. 8B, detection points DPya and DPyb of Y heads 77 yaand 77 yb, respectively, are placed on straight line LX which isparallel to the X-axis.

Now, main controller 20 determines the position of fine movement stageWFS in the Y-axis direction, based on an average of the measurementvalues of the two Y heads 77 ya and 77 yb. Accordingly, in theembodiment, the position of fine movement stage WFS in the Y-axisdirection is measured with a midpoint DP of detection points DPya andDPyb serving as a substantial measurement point. Midpoint DP coincideswith the irradiation point of measurement beams LBx₁ and LBx₂ on gratingRG.

More specifically, in the embodiment, there is a common detection pointregarding measurement of positional information of fine movement stageWFS in the X-axis direction and the Y-axis direction, and this detectionpoint coincides with the exposure position, which is the center ofirradiation area (exposure area) IA of illumination light IL irradiatedon wafer W. Accordingly, in the embodiment, by using encoder system 73,main controller 20 can constantly perform measurement of the positionalinformation of fine movement stage WFS in the XY plane, directly under(at the rear side of fine movement stage WFS) the exposure position whentransferring a pattern of reticle R on a predetermined shot area ofwafer W mounted on fine movement stage WFS. Further, main controller 20measures a rotational amount of fine movement stage WFS in the θzdirection, based on a difference of the measurement values of the pairof Y heads 77 ya and 77 yb.

As shown in FIG. 8A, laser interferometer system 75 makes threemeasurement beams LBz₁, LBz₂, and LBz₃ enter the lower surface of finemovement stage WFS from the tip of measurement arm 71. Laserinterferometer system 75 is equipped with three laser interferometers 75a to 75 c (refer to FIG. 3) that irradiate three measurement beams LBz₁,LBz₂, and LBz₃, respectively.

In laser interferometer system 75, three measurement beams LBz₁, LBz₂,and LBz₃ are emitted in parallel with the Z-axis from each of the threepoints that are not collinear on the upper surface of measurement arm71, as shown in FIGS. 8A and 8B. Now, as shown in FIG. 8B, threemeasurement beams LBz₁, LBz₂, and LBz₃ are each irradiated from threepoints corresponding to the apexes of an isosceles triangle (or anequilateral triangle) whose centroid coincides with the exposure areawhich is the center of irradiation area (exposure area) IA. In thiscase, the outgoing point (irradiation point) of measurement beam LBz₃ islocated on center line CL, and the outgoing points (irradiation points)of the remaining measurement beams LBz₁ and LBz₂ are equidistant fromcanter line CL. In the embodiment, main controller 20 measures theposition in the Z-axis direction, the rotational amount in the θxdirection and the θy direction of fine movement stage WFS, using laserinterferometer system 75. Incidentally, laser interferometers 75 a to 75c are provided on the upper surface (or above) at the end on the −Y sideof measurement arm 71. Measurement beams LBz₁, LBz₂, and LBz₃ emitted inthe −Z direction from laser interferometers 75 a to 75 c travel withinmeasurement arm 71 along the Y-axis direction via reflection surface RPpreviously described, and each of their optical paths is bent so thatthe beams are emitted from the three points described above.

In the embodiment, on the lower surface of fine movement stage WFS, awavelength selection filter (omitted in drawings) which transmits eachmeasurement beam from encoder system 73 and blocks the transmission ofeach measurement beam from laser interferometer system 75 is provided.In this case, the wavelength selection filter also serves as areflection surface of each of the measurement beams from laserinterferometer system 75. As the wavelength selection filter, a thinfilm and the like having wavelength-selectivity is used, and in theembodiment, the wavelength selection filter is provided, for example, onone surface of the transparent plate (main body section 81), and gratingRG is placed on the wafer holder side with respect to the one surface.

As it can be seen from the description so far, main controller 20 canmeasure the position of fine movement stage WFS in directions of sixdegrees of freedom by using encoder system 73 and laser interferometersystem 75 of fine movement stage position measurement system 70. In thiscase, since the optical path lengths of the measurement beams areextremely short and also are almost equal to each other in encodersystem 73, the influence of air fluctuation can mostly be ignored.Accordingly, by encoder system 73, positional information of finemovement stage WFS within the XY plane (including the θz direction) canbe measured with high accuracy. Further, because the substantialdetection points on the grating in the X-axis direction and the Y-axisdirection by encoder system 73 and detection points on the lower surfaceof fine movement stage WFS in the Z-axis direction by laserinterferometer system 75 coincide with the center (exposure position) ofexposure area IA within the XY plane, respectively, generation of theso-called Abbe error caused by a shift within the XY plane of thedetection point and the exposure position is suppressed to asubstantially ignorable degree. Accordingly, by using fine movementstage position measurement system 70, main controller 20 can measure theposition of fine movement stage WFS in the X-axis direction, the Y-axisdirection, and the Z-axis direction with high precision, without anyAbbe errors caused by a shift within the XY plane of the detection pointand the exposure position.

However, as for the Z-axis direction parallel to the optical axis ofprojection optical system PL, positional information in the XY plane offine movement stage WFS is not necessarily measured by encoder system 73at a position at the surface of wafer W, or in other words, the Zposition of the placement surface of grating RG and the surface of waferW do not necessarily coincide. Accordingly, in the case grating RG (inother words, fine movement stage WFS) is inclined with respect to the XYplane, when fine movement stage WFS is positioned based on measurementvalues of each encoder of encoder system 73, a positioning error (a kindof Abbe error) which corresponds to a tilt of grating RG with respect tothe XY plane occurs as a consequence, caused by a difference ΔZ (inother words, a positional shift in the Z-axis direction of the detectionpoint by encoder system 73 and the exposure position) of the Z positionbetween the placement surface of grating RG and the surface of wafer W.However, this positioning error (a position control error) can beobtained by a simple calculation using difference ΔZ, pitching amountθx, and rolling amount θy, and by using these as offsets and performingposition control of fine movement stage WFS based on positionalinformation after correction where measurement values of (each of theencoders of) encoder system 73 have been corrected by the offsets, finemovement stage WFS will not be influenced by the kind of Abbe errordescribed above.

Further, in the configuration of encoder system 73 of the embodiment,measurement errors due to displacement in a direction besides ameasurement direction of grating RG (in other words, fine movement stageWFS), particularly, in inclined (θx, θy) and rotational (θz) directions,may occur. Therefore, main controller 20 makes a correction informationto correct the measurement errors. Now, as an example, a making methodof correction information to correct measurement errors of X encoder 73x will be explained. Incidentally, in the configuration of encodersystem 73 of the embodiment, measurement errors due to displacement inthe X, Y, and Z directions of fine movement stage WFS shall not occur.

a. Main controller 20, first of all, controls coarse movement stagedrive system 51 while monitoring the positional information of waferstage WST using wafer stage position measurement system 16, and drivesfine movement stage WFS along with coarse movement stage WCS into ameasurement area of X encoder 73 x.b. Next, main controller 20 controls fine movement stage drive system 52based on measurement results of laser interferometer system 75 and Yencoders 73 ya and yb, and fixes fine movement stage WFS so that roilingamount θy and yawing amount θz are both zero, and pitching θx is apredetermined amount (e.g., 200 μrad).c. Next, main controller 20 controls fine movement stage drive system 52based on the measurement results of laser interferometer system 75 and Yencoders 73 ya and yb, and drives fine movement stage WFS in the Z-axisdirection within a predetermined range, such as for example, −100 μm to+100 μm, while maintaining the attitude (pitching amount θx, rollingamount θy=0, yawing amount θz=0) of fine movement stage WFS describedabove, so as to measure positional information in the X-axis directionof fine movement stage WFS, using X encoder 73 x.d. Next, main controller 20 controls fine movement stage drive system 52based on the measurement results of laser interferometer system 75 and Yencoders 73 ya and yb, and changes pitching amount θx in a predeterminedrange, such as for example, −200 μm to +200 μm, while keeping rollingamount θy and yawing amount θz of fine movement stage WFS fixed. Now,pitching amount θx shall be changed by a predetermined pitch Δθx. Then,a processing similar to c. is to be carried out for each pitching amountθx.e. By the processing b. to d. described above, measurement results of Xencoder 73 x to θx and Z when θy=θz=0 can be obtained. The measurementresults are plotted, with the Z position of fine movement stage WFS onthe horizontal axis and measurement values of X encoder 73 x on thevertical axis, and these relations plotted versus each pitching amountθx, as shown in FIG. 9. This allows a plurality of straight lines havingdifferent slopes to be obtained by joining the plotted points for eachpitching amount θx, and an intersecting point of these straight linesshow a true measurement value of X encoder 73 x. Therefore, by choosingthe intersecting point as an origin, the vertical axis can be read as ameasurement error of X encoder 73 x. Now, the Z position at the originshall be Z_(x0). The measurement errors obtained by the processingdescribed above of X encoder 73 x with respect to θx and Z when θy=θz=0,serves as a θx correction information.f. Similar to the processing b. to d. described above, main controller20 fixes both pitching amount θx and yawing amount θz of fine movementstage WFS to zero, and changes rolling amount θy of fine movement stageWFS. And, for each θy, fine movement stage WFS is driven in the Z-axisdirection and positional information in the X-axis direction of finemovement stage WFS is measured using X encoder 73 x. Using results whichare obtained, a relation between a Z position of fine movement stage WFSwith respect to each θy when θx=θz=0 and measurement values of X encoder73 x are plotted, similar to FIG. 9. Furthermore, an intersecting pointof a plurality of straight lines having different slopes which can beobtained by joining the plotted points for each rolling amount θy ischosen, or in other words, a measurement value of X encoder 73 xcorresponding to the intersecting point serves as a true measurementvalue, and the shift from the true measurement value is to be ameasurement error. Now, the Z position at the origin shall be zy0. Themeasurement errors obtained by the processing described above of Xencoder 73 x with respect to θy and Z when θx=θz=0, serves as a θycorrection information.g. Similar to the processing b. to d. and f., main controller 20 obtainsthe measurement error of X encoder 73 x with respect to θz and Z whenθx=θy=0. Incidentally, the Z position at the origin shall be zz0 as inthe previous description. The measurement errors obtained by suchprocessing serve as a θz correction information.

Incidentally, the θx correction information can be stored in memory, ina table data format consisting of discrete measurement errors of anencoder at each measurement point of pitching amount θx and the Zposition, or in a form of a trial function of pitching amount θx and theZ position which indicates a measurement error of the encoder. In thelatter case, an undetermined coefficient of the trial function is to bedetermined, for example, by the least-squares method using themeasurement error of the encoder. The same can be said for the θycorrection information and the θz correction information.

Incidentally, the measurement error of the encoder generally depends onall of pitching amount θx, rolling amount θy, and yawing amount θz.However, it is known that the degree of dependence is small.Accordingly, it can be regarded that the measurement error of theencoder due to the attitude change of grating RG depend on each of θx,θy and θz, independently. In other words, the measurement error (allmeasurement errors) of the encoder due to the attitude change of gratingRG can be given, for example, in the form of formula (1) below, in alinear sum of the measurement error with respect to each of θx; θy, andθz.

$\begin{matrix}\begin{matrix}{{\Delta\; x} = {\Delta\; x\;\left( {Z,{\theta\; x},{\theta\; y},{\theta\; z}} \right)}} \\{= {{\theta\; x\mspace{11mu}\left( {z - z_{x\; 0}} \right)} + {\theta\; y\mspace{11mu}\left( {z - z_{y\; 0}} \right)} + {\theta\; z\mspace{11mu}\left( {z - z_{z\; 0}} \right)}}}\end{matrix} & (1)\end{matrix}$

Main controller 20 makes correction information θx Correctioninformation, θy correction information, θz correction information) tocorrect the measurement errors of Y encoders 73 a and 73 yb, accordingto a procedure similar to the making procedure of the correctioninformation described above. All measurement errors Δy=Δy (Z, θx, θy,θz) can be given in a similar form as in formula (1) above.

Main controller 20 performs the processing described above, such as atthe time of start-up of exposure apparatus 100, during an idle state, orat the time of wafer exchange of a predetermined number, as in, forexample, a number of units, and makes the correction information θxcorrection information, θy correction information, θz correctioninformation) of Y encoders 73 a and 73 yb described above. Then, maincontroller 20 monitors the θx, θy, θz, and Z positions of fine movementstage WFS while exposure apparatus 100 is operating, and by using thesemeasurement results, obtains error correction amount Δx and Δy of Xencoder 73 x, and Y encoders 73 ya and 73 yb from the correctioninformation θx correction information, θy correction information, θzcorrection information).

Then, by main controller 20 further correcting the measurement errors ofthe measurement values after correction, which are the measurementvalues of X encoder 73 x, and Y encoders 73 ya and 73 yb that have beencorrected by the offset previously described, using error correctionamount and Δy, measurement errors of encoder system 73 which occur dueto the displacement of fine movement stage WFS to a tilt (θx, θy) androtational (θz) directions are corrected. Or, a target position of finemovement stage WFS can be corrected, using such error correction amountand offset. In this approach as well, a similar effect can be obtainedas in the case of correcting the measurement errors of encoder system73. Incidentally, the measurement values of X encoder 73 x, and Yencoders 73 ya and 73 yb can further be corrected by the offsetpreviously described, after the correction using the error correctionamount, or the measurement values of X encoder 73 x, and Y encoders 73ya and 73 yb can be corrected, simultaneously using the error correctionamount and the offset.

In exposure apparatus 100 of the embodiment which it is configured inthe manner described above, on manufacturing a device, first of all,main controller 20 detects the second fiducial marks on measurementplate 86 of fine movement stage WFS, using wafer alignment system ALG.Subsequently, main controller 20 performs wafer alignment (EnhancedGlobal Alignment (EGA) and the like which is disclosed in, for example,U.S. Pat. No. 4,780,617 and the like) and the like using wafer alignmentsystem ALG. Incidentally, in exposure apparatus 100 of the embodiment,because wafer alignment system ALG is placed away in the Y-axisdirection from projection unit PU, position measurement of fine movementstage WFS by the encoder system (measurement arm) of fine movement stageposition measurement system 70 cannot be performed when, performing thewafer alignment. Therefore, wafer alignment is to be performed, whilemeasuring the position of wafer W (fine movement stage WFS) via a laserinterferometer system (not shown) similar to wafer stage positionmeasurement system 16 previously described. Further, because waferalignment system ALG and projection unit PU are distanced, maincontroller 20 converts array coordinates of each shot area on wafer Wacquired from the wafer alignment into array coordinates which are basedon the second fiducial marks.

Then, prior to the beginning of exposure, main controller 20 performsreticle alignment in a procedure (a procedure disclosed in, for example,U.S. Pat. No. 5,646,413 and the like) similar to a normal scanningstepper, using the pair of reticle alignment systems RA₁ and RA₂previously described, and the pair of first fiducial marks onmeasurement plate 86 of fine movement stage WFS and the like. Then, maincontroller 20 performs exposure operation by the step-and-scan method,based on results of the reticle alignment and the results of the waferalignment (array coordinates which uses the second fiducial marks ofeach of the shot areas on wafer W), and transfers the pattern of reticleR on each of the plurality of shot areas on wafer W. This exposureoperation is performed by alternately repeating a scanning exposureoperation where synchronous movement of reticle stage RST and waferstage WST previously described is performed, and a movement (stepping)operation between shots where wafer stage WST is moved to anacceleration starting position for exposure of the shot area. In thiscase, scanning exposure by the liquid immersion exposure is performed.In exposure apparatus 100 of the embodiment, during the series ofexposure operations, main controller 20 measures a position of finemovement stage WFS (wafer W) using fine movement stage positionmeasurement system 70, and the measurement values of each encoder ofencoder system 73 is corrected as described above, and the position ofwafer Win the XY plane is controlled, based on the measurement values ofeach encoder of encoder system 73 after the correction. Further, thefocus leveling control of wafer W during exposure is performed, based onthe measurement results of multipoint AF system AF by main controller 20as is previously described.

Incidentally, while wafer W has to be scanned with high acceleration inthe Y-axis direction at the time of scanning exposure operationdescribed above, in exposure apparatus 100 of the embodiment, maincontroller 20 scans wafer W in the Y-axis direction by driving (refer tothe black arrow in FIG. 10A) only fine movement stage WFS in the Y-axisdirection (and in directions of the other five degrees of freedom, ifnecessary), without driving coarse movement stage WCS in principle atthe time of scanning exposure operation as shown in FIG. 10A. This isbecause when moving only fine movement stage WFS, weight of the driveobject is lighter when comparing with the case where coarse movementstage WCS is driven, which allows an advantage of being able to drivewafer W with high acceleration. Further, because position measuringaccuracy of fine movement stage position measurement system 70 is higherthan wafer stage position measurement system 16 as previously described,it is advantageous to drive fine movement stage WFS at the time ofscanning exposure. Incidentally, at the time of this scanning exposure,coarse movement stage WCS is driven to the opposite side of finemovement stage WFS by an operation of a reaction force (refer to theoutlined arrow in FIG. 10A) by the drive of fine movement stage WFS.More specifically, because coarse movement stage WCS functions as acountermass, momentum of the system consisting of the entire wafer stageWST is conserved and centroid shift does not occur, inconveniences suchas unbalanced load acting on base board 12 by the scanning drive of finemovement stage WFS do not occur.

Meanwhile, when movement (stepping) between shots in the X-axisdirection is performed, because movement capacity in the X-axisdirection of fine movement stage WFS is small, main controller 20 moveswafer W in the X-axis direction by driving coarse movement stage WCS inthe X-axis direction as shown in FIG. 10B.

As described above, according to exposure apparatus 100 of theembodiment, the positional information of fine movement stage WFS in then plane is measured by main controller 20, using encoder system 73 offine movement stage position measurement system 70 having measurementarm 71 previously described. In this case, because each of the heads offine movement stage position measurement system 70 are placed in thespace within coarse movement stage WCs, there is only space between finemovement stage WFS and the heads. Accordingly, each of the heads can beplaced close to fine movement stage WFS (grating RG), which allowsmeasurement of the positional information of fine movement stage WFS byfine movement stage position measurement system 70 with high precision,which in its turn allows a highly precise drive of fine movement stageWFS via fine movement stage drive system 52 (and coarse movement stagedrive system 51) by main controller 20. Further, in this case,irradiation points of the measurement beams of each of the heads ofencoder system 73 and laser interferometer system 75 configuring finemovement stage position measurement system 70 emitted from measurementarm 71 on grating RG coincide with the center (exposure position) ofirradiation area (exposure area) IA of exposure light IL irradiated onwafer W. While the irradiation point of all the measurement beams doesnot always coincide with the exposure center here, the extent of theinfluence of the Abbe error is suppressible, or negligible. Accordingly,main controller 20 can measure the positional information of finemovement stage WFS with high accuracy, without being affected byso-called Abbe error which occurs due to a displacement between thedetection point and the exposure position within the XY plane.

Further, by using difference ΔZ of the Z position between the placementsurface of grating RG and the surface of wafer W, and angle ofinclination θx and θy of grating RG more specifically, fine movementstage WFS), main controller 20 obtains the positioning error (positioncontrol error, a kind of Abbe error) corresponding to the tilt ofgrating RG with respect to the XY plane caused due to difference ΔZ, anduses this as an offset, to correct the measurement values of (eachencoder) of encoder system 73 by the offset. Furthermore, maincontroller 20 obtains error correction amount θx and θy of X encoder 73x, and Y encoders 73 ya and 73 yb from the correction information (θxcorrection information, θy correction information, θz correctioninformation), and further corrects the measurement values of X encoder73 x, and Y encoders 73 ya and 73 yb. Accordingly, positionalinformation of fine movement stage WFS can be measured with highprecision by encoder system 73. Further, because optical path lengths inthe atmosphere of the measurement beams of each of the heads of encodersystem 73 can be made extremely short by placing measurement arm 71right under grating RG, the influence of air fluctuation is reduced, andalso in this point, the positional information of fine movement stageWFS can be measured with high accuracy.

Further, according to exposure apparatus 100 of the embodiment, maincontroller 20 can drive fine movement stage WFS with good precision,based on highly precise measurement results of positional information offine movement stage WFS. Accordingly, main controller 20 can drive waferW mounted on fine movement stage WFS in sync with reticle stage RST(reticle R) with good precision, and can transfer a pattern of reticle Ron wafer W with good precision by scanning exposure.

Incidentally, in the embodiment above, the case has been described wheremain controller 20 corrects measurement errors in the direction besidesthe measurement direction of grating RG (More specifically, finemovement stage WFS) especially measurement errors occurring due to thedisplacement in tilt (θx, θy) and rotational (θz) directions, along withpositioning errors (position control errors, a kind of Abbe error)corresponding to the tilt of grating RG with respect to the XY planecaused due to difference ΔZ that are included in the measurement valuesof each encoder of encoder system 73 on exposure. However, because themeasurement errors in the latter case are usually small in comparisonwith the measurement errors in the former case, correction only on themeasurement errors in the former case is acceptable.

Incidentally, in the embodiment above, while alignment of the wafer wasperformed measuring the position of wafer W (fine movement stage WFS)via the laser interferometer system (not shown), besides this, a secondfine movement stage position measurement system including a measurementarm having a configuration similar to measurement arm 71 of finemovement stage position measurement system 70 can be arranged in thevicinity of wafer alignment system ALG, and position measurement of thefine movement stage within the XY plane can be performed using this atthe time of the wafer alignment. Further, in this case, correction ofthe Abbe error can be performed as in the manner previously described.

Incidentally, in the embodiment described above, the case has beendescribed where the fine movement stage is supported movable withrespect to the coarse movement stage, and a sandwich structure whichvertically sandwiches a coil unit between a pair of magnetic units isemployed as fine movement stage drive system 52 which drives the finemovement stage in directions of six degree of freedom. However, as wellas this, the fine movement stage drive system can employ a structurewhere a magnet unit is vertically sandwiched by a pair of coil units, ora sandwich structure does not have to be employed. Further, a coil unitcan be placed in the fine movement stage, and a magnet unit can beplaced in the coarse movement stage.

Further, in the embodiment and described above, while the fine movementstage was driven in directions of six degrees of freedom by finemovement stage drive system 52, the fine movement stage does notnecessarily have to be driven in directions of six degrees of freedom.For example, the fine movement stage drive system does not have to drivethe fine movement stage in the θx direction.

Incidentally, in the embodiment above, while fine movement stage WFS issupported in a noncontact manner by coarse movement stage WCs by theaction of the Lorentz force (electromagnetic force), besides this, forexample, a vacuum preload type hydrostatic air bearings and the like canbe arranged on fine movement stage WFS so that it is supported bylevitation with respect to support coarse movement stage WCS. Further,fine movement stage drive system 52 is not limited to the magnet movingtype described above, and can also be a moving coil type as well.Furthermore, fine movement stage WFS can also be supported in contactwith coarse movement stage WCS. Accordingly, as fine movement stagedrive system 52 which drives fine movement stage WFS with respect tocoarse movement stage WCS, for example, a rotary motor and a ball screw(or a feed screw) can also be combined for use.

Incidentally, the fine movement stage position measurement system can beconfigured so that position measurement is possible within the totalmovement range of wafer stage WST. In this case, wafer stage positionmeasurement system 16 will not be required. Further, in the embodimentabove, base board 12 can be a counter mass which can move by anoperation of a reaction force of the drive force of the wafer stage. Inthis case, coarse movement stage does not have to be used as a countermass, or when the coarse movement stage is used as a counter mass as inthe embodiment described above, the weight of the coarse movement stagecan be reduced.

Incidentally, in the embodiment described above, while the case has beendescribed where the entire fine movement stage position measurementsystem is made of, for example, glass, and is equipped with ameasurement arm in which light can proceed inside, besides this, atleast only the part where each of the laser beams previously describedproceed in the measurement arm has to be made of a solid member throughwhich light can pass, and the other sections, for example can be amember that does not transmit light, or have a hollow structure.

Further, as a measurement arm, for example, a light source or aphotodetector can be built in the tip of the measurement arm, as long asa measurement beam can be irradiated from the section facing thegrating. In this case, the measurement beam of the encoder does not haveto proceed inside the measurement arm. Further, in the measurement arm,the part (beam optical path segment) where each laser beam proceeds canbe hollow. Or, in the case of employing a grating interference typeencoder system as the encoder system, the optical member on which thediffraction grating is formed only has to be provided on an arm that haslow thermal expansion, such as for example, ceramics, Invar and thelike. This is because especially in an encoder system, the space wherethe beam separates is extremely narrow (short) so that the system is notaffected by air fluctuation as much as possible. Furthermore, in thiscase, the temperature can be stabilized by supplying gas whosetemperature has been controlled to the space between fine movement stage(wafer holder) and the arm (and beam optical path). Furthermore, themeasurement arm need not have any particular shape.

Further, the fine movement stage position measurement system does notalways have to be equipped with a measurement arm, and will suffice aslong as it has a head which is placed facing grating RG inside the spaceof the coarse movement stage and receives a diffraction light fromgrating RG of at least one measurement beam irradiated on grating RG,and can measure the positional information of fine movement stage WFS atleast within the XY plane, based on the output of the head.

Further, in the embodiment above, while an example has been shown whereencoder system 73 is equipped with an X head and a pair of Y heads,besides this, for example, one or two two-dimensional heads (2D heads)whose measurement directions are in two directions, which are the X-axisdirection and the Y-axis direction, can be provided. In the case two 2Dheads are provided, detection points of the two heads can be arranged tobe two points which are spaced equally apart in the X-axis direction onthe grating, with the exposure position serving as the center.

Incidentally, fine movement stage position measurement system 70 canmeasure positional information in directions of six degrees of freedomof the fine movement stage only by using encoder system 73, withoutbeing equipped with laser interferometer system 75. In this case, anencoder which can measure positional information, for example, in atleast one of the X-axis direction and the Y-axis direction, and theZ-axis direction can also be used. As the encoder used in this case, asensor head system for measuring variation disclosed in, for example,U.S. Pat. No. 7,561,280, can be used. And, for example, by irradiatingmeasurement beams from a total of three encoders including an encoder(such as the sensor head system for measuring variation described above)which can measure positional information in the X-axis direction and theZ-axis direction and an encoder (such as the sensor head system formeasuring variation described above) which can measure positionalinformation in the Y-axis direction and the Z-axis direction, on threemeasurement points that are noncollinear, and receiving each of thereturn lights from grating RG, positional information of the movablebody on which grating RG is provided can be measured in directions ofsix degrees of freedom. Further, the configuration of encoder system 73is not limited to the embodiment described above, and is arbitrary. Forexample, a 3D head which can measure positional information in each ofthe X-axis, the Y-axis, and the Z-axis directions can be used.

Incidentally, in the embodiment above, while the grating was placed onthe upper surface of the fine movement stage, that is, a surface thatfaces the wafer, as well as this, for example, grating RG can be formedon the lower surface of wafer holder WH which holds wafer W, as shown inFIG. 11. In this case, even when wafer holder WH expands or aninstalling position to fine movement stage WFS shifts during exposure,this can be followed up when measuring the position of the wafer holder(wafer). Grating RG can be fixed to the lower surface of wafer holderWH. In this case, a surface of the transparent plate on which grating RGis fixed or formed can be placed in contact or close to the rear surfaceof the wafer holder.

Further, grating RG can be placed on the lower surface of the finemovement stage, and in such a case, grating RG can be fixed to or formedon an opaque member such as ceramics. Further, in this case, the finemovement stage does not have to be a solid member through which lightcan pass because the measurement beam irradiated from the encoder headdoes not proceed inside the fine movement stage, and fine movement stagecan have a hollow structure with the piping, wiring and like placedinside, which allows the weight of the fine movement stage to bereduced. In this case, a protective member (a cover glass) can beprovided on the surface of grating RG. Or, the hold wafer holder andgrating RG can simply be held by a conventional fine movement stage.Further, the wafer holder can be made of a solid glass member, andgrating RG can be placed on the upper surface (a wafer mounting surface)of the glass member.

Further, in the embodiment above, the case has been described where theexposure apparatus is a liquid immersion type exposure apparatus.However, the present invention is not limited to this, and theembodiment above can also be applied suitably in a dry type exposureapparatus that performs exposure of wafer W without liquid (water).

Incidentally, in the embodiment above, while the case has been describedwhere the exposure apparatus is a scanning stepper, besides this, theembodiment above can also be applied to a static exposure apparatus suchas a stepper. Even in the case of a stepper, by measuring the positionof a stage on which the object subject to exposure is mounted using anencoder, position measurement error caused by air fluctuation cansubstantially be nulled, which is different from when measuring theposition of this stage using an interferometer, and it becomes possibleto control the position of the stage with high precision based on themeasurement values of the encoder, which in turn makes it possible totransfer a reticle pattern on the object with high precision. Further,the embodiment above can also be applied to a reduction projectionexposure apparatus by a step-and-stitch method that synthesizes a shotarea and a shot area.

Further, the magnification of the projection optical system in theexposure apparatus of the embodiment above is not only a reductionsystem, but also may be either an equal magnifying system or amagnifying system, and projection optical system PL is not only adioptric system, but also may be either a catoptric system or acatodioptric system, and in addition, this projected image may be eitheran inverted image or an upright image.

In addition, the illumination light IL is not limited to ArF excimerlaser light (with a wavelength of 193 nm), but may be ultraviolet light,such as KrF excimer laser light (with a wavelength of 248 nm), or vacuumultraviolet light, such as F₂ laser light (with a wavelength of 157 nm).As disclosed in, for example, U.S. Pat. No. 7,023,610, a harmonic wave,which is obtained by amplifying a single-wavelength laser beam in theinfrared or visible range emitted by a DFB semiconductor laser or fiberlaser, with a fiber amplifier doped with, for example, erbium (or botherbium and ytterbium), and by converting the wavelength into ultravioletlight using a nonlinear optical crystal, can also be used as vacuumultraviolet light.

In addition, the illumination light IL of the exposure apparatus 10 inthe abovementioned embodiment is not limited to light with a wavelengthof 100 nm or greater, and, of course, light with a wavelength of lessthan 100 nm may be used. For example, the embodiment above can beapplied to an EUV exposure apparatus that uses an EUV (ExtremeUltraviolet) light in a soft X-ray range (e.g., a wavelength range from5 to 15 nm). In addition, the embodiment above can also be applied to anexposure apparatus that uses charged particle beams such as an electronbeam or an ion beam.

Further, in the embodiment above, a transmissive type mask (reticle) isused, which is a transmissive substrate on which a predetermined lightshielding pattern (or a phase pattern or a light attenuation pattern) isformed. Instead of this reticle, however, as is disclosed in, forexample, U.S. Pat. No. 6,778,257, an electron mask (which is also calleda variable shaped mask, an active mask or an image generator, andincludes, for example, a DMD (Digital Micromirror Device) that is a typeof a non-emission type image display device (spatial light modulator) orthe like) on which a light-transmitting pattern, a reflection pattern,or an emission pattern is formed according to electronic data of thepattern that is to be exposed can also be used. In the case of usingsuch a variable shaped mask, because the stage where a wafer, a glassplate or the like is mounted is scanned with respect to the variableshaped mask, an equivalent effect as the embodiment above can beobtained by measuring the position of this stage using an encoder systemand a laser interferometer system.

Further, as is disclosed in, for example, PCT International. PublicationNo. 2001/035168, the embodiment above can also be applied to an exposureapparatus (lithography system) that forms line-and-space patterns on awafer W by forming interference fringes on wafer W.

Moreover, as disclosed in, for example, U.S. Pat. No. 6,611,316, theembodiment above can also be applied to an exposure apparatus thatsynthesizes two reticle patterns via a projection optical system andalmost simultaneously performs double exposure of one shot area by onescanning exposure.

Incidentally, an object on which a pattern is to be formed (an objectsubject to exposure to which an energy beam is irradiated) in theembodiment above is not limited to a wafer, but may be other objectssuch as a glass plate, a ceramic substrate, a film member, or a maskblank.

The application of the exposure apparatus is not limited to an exposureapparatus for fabricating semiconductor devices, but can be widelyadapted to, for example, an exposure apparatus for fabricating liquidcrystal devices, wherein a liquid crystal display device pattern istransferred to a rectangular glass plate, as well as to exposureapparatuses for fabricating organic electroluminescent displays, thinfilm magnetic heads, image capturing devices (e.g., CCDs) micromachines,and DNA chips. In addition to fabricating microdevices likesemiconductor devices, the embodiment above can also be adapted to anexposure apparatus that transfers a circuit pattern to a glasssubstrate, a silicon wafer, or the like in order to fabricate a reticleor a mask used by a visible light exposure apparatus, an EUV exposureapparatus, an X-ray exposure apparatus, an electron beam exposureapparatus, and the like.

Incidentally, the movable body apparatus of the present invention can beapplied not only to the exposure apparatus, but can also be appliedwidely to other substrate processing apparatuses (such as a laser repairapparatus, a substrate inspection apparatus and the like), or toapparatuses equipped with a movable stage of a position settingapparatus of a sample or a wire bonding apparatus in other precisionmachines.

Incidentally, the disclosures of all publications, the PCT InternationalPublications, the U.S. Patent Applications and the U.S. Patents that arecited in the description so far related to exposure apparatuses and thelike are each incorporated herein by reference.

Electronic devices such as semiconductor devices are manufacturedthrough the steps of; a step where the function/performance design ofthe device is performed, a step where a reticle based on the design stepis manufactured, a step where a wafer is manufactured from siliconmaterials, a lithography step where the pattern of a mask (the reticle)is transferred onto the wafer by the exposure apparatus (patternformation apparatus) and the exposure method in the embodimentpreviously described, a development step where the wafer that has beenexposed is developed, an etching step where an exposed member of an areaother than the area where the resist remains is removed by etching, aresist removing step where the resist that is no longer necessary whenetching has been completed is removed, a device assembly step (includinga dicing process, a bonding process, the package process), inspectionsteps and the like. In this case, in the lithography step, because thedevice pattern is formed on the wafer by executing the exposure methodpreviously described using the exposure apparatus of the embodiment, ahigh y integrated device can be produced with good productivity.

While the above-described embodiment of the present invention is thepresently preferred embodiment thereof, those skilled in the art oflithography systems will readily recognize that numerous additions,modifications, and substitutions may be made to the above-describedembodiments without departing from the spirit and scope thereof. It isintended that all such modifications, additions, and substitutions fallwithin the scope of the present invention, which is best defined by theclaims appended below.

What is claimed is:
 1. A movable body apparatus, comprising: a movablebody which is movable substantially along a predetermined plane holdingan object, and has a grating placed on a rear surface side of the objectsubstantially parallel with the predetermined plane; a measurementsystem which irradiates a measurement light of a predeterminedwavelength toward the grating on an opposite side of a mounting surfaceof the object, receives diffraction light from the grating originatingfrom the measurement light, and measures positional information of themovable body in a measurement direction within the predetermined plane;and a drive system which drives the movable body, based on thepositional information in the measurement direction of the movable bodyand correction information of a measurement error caused by a tilt ofthe movable body included in the positional information, wherein themovable body has a space inside, and the measurement system has ameasurement member which is located in the space when the movable bodyis in an area within a predetermined range including a predeterminedpoint where the movable body is to be positioned in the predeterminedplane, and on the measurement member, at least a part of a head isprovided which irradiates the measurement light on the grating andreceives a diffraction light from the grating originating from themeasurement light.
 2. The movable body apparatus according to claim 1,further comprising: a tilt measurement system which measures tiltinformation with respect to the predetermined plane of the movable body.3. The movable body apparatus according to claim 2, wherein thecorrection information includes a first correction information on ameasurement error which occurs due to a tilt of the movable bodycorresponding to a distance between a surface of the object and a planeon which the grating of the movable body is placed.
 4. The movable bodyapparatus according to claim 3, wherein the correction informationfurther includes a second correction information on a measurement errorwhich occurs due to a tilt of the plane on which the grating of themovable body is placed.
 5. The movable body apparatus according to claim4, further comprising: a controller which makes the movable body vary ina plurality of different attitudes based on the positional informationand the tilt information, measures positional information in themeasurement direction of the movable body at different positions in adirection perpendicular to the predetermined plane while maintainingeach attitude, and performs one of making and revising the secondcorrection information based on the positional information.
 6. Themovable body apparatus according to claim 2, wherein the tiltmeasurement system irradiates at least three measurement beams that havea wavelength different from the predetermined wavelength on a planesubstantially parallel to the predetermined plane of the movable body,and receives a reflected light from the movable body of each of themeasurement beams.
 7. The movable body apparatus according to claim 1,wherein the drive system corrects one of a target position to drive themovable body and the positional information, based on the correctioninformation.
 8. The movable body apparatus according to claim 1, whereinthe grating includes a diffraction grating whose periodic direction isin a direction which is one of a first and a second directions parallelto a first axis and a second axis, respectively, which are orthogonal toeach other within the predetermined plane, and the measurement systemmeasures positional information in the one direction of the movablebody.
 9. The movable body apparatus according to claim 8, wherein thegrating further includes a diffraction grating whose periodic directionis in the other direction of the first and the second directions withinthe predetermined plane, and the measurement system measures positionalinformation of the movable body in the other direction as well.
 10. Themovable body apparatus according to claim 9, wherein the grating is atwo-dimensional grating whose periodic directions are in the first andthe second directions.
 11. The movable body apparatus according to claim1, wherein the grating is placed between the mounting surface of theobject of the movable body and a plane parallel to the predeterminedplane opposite to the mounting surface, and the measurement systemirradiates the measurement light on the grating.
 12. The movable bodyapparatus according to claim 1, wherein the movable body includes aholding member which holds the object and also has the grating placed ata rear surface of the holding member, and a table on which the holdingmember is mounted and whose inside the measurement light is transmitted.13. The movable body apparatus according to claim 12, wherein theholding member is detachable with respect to the table.
 14. The movablebody apparatus according to claim 1, wherein the movable body includes atransparent member on which the measurement light is incident and whichalso has the grating formed on a surface substantially parallel to thepredetermined plane, and a holding member that holds the object and isalso arranged on the surface side with respect to the transparentmember.
 15. The movable body apparatus according to claim 1, furthercomprising: a movable member which can movably support the movable bodyrelatively at least within a plane parallel to the predetermined plane,and can move at least along the predetermined plane, whereby the drivesystem drives the movable body in one of an individual manner and anintegral manner with the movable member.
 16. The movable body apparatusaccording to claim 1, wherein the measurement light is irradiated on oneof the predetermined point and in a vicinity of the predetermined point.17. An exposure apparatus that forms a pattern on an object by anirradiation of an energy beam, the apparatus comprising: a patterningdevice that irradiates the energy beam on the object; and the movablebody apparatus according to claim 1 in which the object on which anenergy beam is irradiated is held by the movable body.
 18. The exposureapparatus according to claim 17, wherein the measurement light isirradiated on a predetermined point in an irradiation area of the energybeam.
 19. The exposure apparatus according to claim 18, wherein thepredetermined point is an exposure center of the patterning device. 20.A device manufacturing method, including exposing a substrate using theexposure apparatus according to claim 17; and developing the substratewhich has been exposed.
 21. An exposure method in which an energy beamis irradiated on an object to form a predetermined pattern on theobject, the method comprising: measuring positional information of amovable body, which holds the object and also has a grating placedsubstantially parallel to a predetermined plane on a rear surface sideof the object, in a measurement direction within the predeterminedplane, by moving the movable body along the predetermined plane,irradiating a measurement light of a predetermined wavelength toward thegrating on an opposite side of a mounting surface of the object, andreceiving a diffraction light from the grating originating from themeasurement light; and driving the movable body, based on the positionalinformation in the measurement direction of the movable body andcorrection information of a measurement error caused by a tilt of themovable body included in the positional information, wherein the movablebody has a space inside, and in the measuring, the measurement isperformed using a head, at least a part of the head being provided on ameasurement member located in the space when the movable body is in anarea within a predetermined range including a predetermined point wherethe movable body is to be positioned in the predetermined plane, and thehead irradiating the measurement light on the grating and receiving adiffraction light from the grating originating from the measurementlight.
 22. The exposure method according to claim 21, furthercomprising: measuring tilt information with respect to the predeterminedplane of the movable body, wherein in the driving, the movable body isdriven based on the positional information in the measurement directionof the movable body and the correction information of the measurementerror corresponding to the tilt information which has been measured. 23.The exposure method according to claim 22, wherein the correctioninformation includes a first correction information on a measurementerror which occurs due to a tilt of the movable body corresponding to adistance between a surface of the object and a plane on which thegrating of the movable body is placed.
 24. The exposure method accordingto claim 23, wherein the correction information further includes asecond correction information on a measurement error which occurs due toa tilt of the plane on which the grating of the movable body is placed.25. The exposure method according to claim 24, further comprising:performing one of making and revising the second correction information,by making the movable body vary in a plurality of different attitudesbased on the positional information and the tilt information, measuringpositional information in the measurement direction of the movable bodyat different positions in a direction perpendicular to the predeterminedplane while maintaining each attitude, and performing one of making andrevising the second correction information based on the positionalinformation that has been measured.
 26. The exposure method according toclaim 22, wherein on measuring the tilt information, a measurementsystem is used which irradiates at least three measurement beams thathave a wavelength different from the predetermined wavelength on a planesubstantially parallel to the predetermined plane of the movable body,and receives a reflected light from the movable body of each of themeasurement beams.
 27. The exposure method according to claim 21,wherein in the driving, one of a target position to drive the movablebody and the positional information is corrected, based on thecorrection information.
 28. The exposure method according to claim 21,wherein the grating includes a diffraction grating whose periodicdirection is in a direction which is one of a first and a seconddirections parallel to a first axis and a second axis, respectively,which are orthogonal to each other within the predetermined plane, andin the measuring, positional information in the one direction of themovable body is measured.
 29. The exposure method according to claim 28,wherein the grating further includes a diffraction grating whoseperiodic direction is in the other direction of the first and the seconddirections within the predetermined plane, and in the measuring,positional information of the movable body in the other direction ismeasured as well.
 30. The exposure method according to claim 29, whereinthe grating is a two-dimensional grating whose periodic directions arein the first and the second directions.
 31. The exposure methodaccording to claim 21, wherein the grating is placed between themounting surface of the object of the movable body and a plane parallelto the predetermined plane opposite to the mounting surface, and in themeasuring, the measurement light is irradiated on the grating, and adiffraction light from the grating originating from the measurementlight is received.
 32. The exposure method according to claim 21,wherein the movable body includes a holding member which holds theobject and also has the grating placed at a rear surface of the holdingmember, and a table on which the holding member is mounted and whoseinside the measurement light is transmitted.
 33. The exposure methodaccording to claim 32, wherein the holding member is detachable withrespect to the table.
 34. The exposure method according to claim 21,wherein the movable body includes a transparent member on which themeasurement light is incident and which also has the grating formed on asurface substantially parallel to the predetermined plane, and a holdingmember that holds the object and is also arranged on the surface sidewith respect to the transparent member.
 35. The exposure methodaccording to claim 21, further comprising: supporting the movable bodyby a movable member which is movable at least along the predeterminedplane, relatively movable at least within a plane parallel to thepredetermined plane, whereby in the driving, the movable body is drivenin one of an individual manner and an integral manner with the movablemember.
 36. The exposure method according to claim 21, wherein themeasurement light is irradiated on one of the predetermined point and ina vicinity of the predetermined point.
 37. The exposure method accordingto claim 21, wherein the measurement light is irradiated on apredetermined point in an irradiation area of the energy beam.
 38. Theexposure method according to claim 37, wherein the predetermined pointis an exposure center.
 39. A device manufacturing method, includingexposing a substrate using the exposure method according to claim 21;and developing the substrate which has been exposed.